EP1882600B1 - Twist beam axle - Google Patents

Description

The invention relates to a torsion beam axle of a two-lane vehicle with a left-side and a right-side leading the respective rear trailing arm, which are interconnected via a cross member and facing away with the wheel viewed in the direction of travel front end directly or indirectly mounted on the vehicle body, and with a left-sided and a right-hand side substantially aligned in the vehicle longitudinal direction leaf spring element, which opposes a substantially vertical displacement of the rear wheel in the direction of the vehicle body spring force and its front end in the direction of travel with the associated trailing arm is connected and viewed with its rear end in the direction of travel behind the essentially defined by the axes of rotation of the rear wheels Achsquerebene is supported via a transverse forces receiving coupling element on the vehicle body. The prior art is in addition to the EP 1 216 859 A2 especially on the EP 1 024 037 A1 directed.

The known under the name "torsion beam axle" the specialist rear axle construction is widely used, especially because of its cost-effective design and the advantages in terms of space in motor vehicles with front-wheel drive. However, it can also be used on other two-lane vehicles as well as on vehicle trailers. Essentially, a torsion-beam axle is characterized in that a left-side and a right-side the respective rear wheel leading trailing arm in Fzg.-direction before the geometric Fzg.-rear axle (or in front of the vertical axis transverse plane containing them) connected to each other via a cross member and with their the Wheel facing away in the direction of travel considered front end via elastic bearings are hinged to the vehicle body. In addition to the properties already mentioned, a torsion beam axle offers the advantage of having desired kinematic towing properties and camber properties during rolling movements of the vehicle body, but to produce almost no changes in toe-in and camber during pure lifting movements.

A disadvantage of composite beam axes, however, is their concept-typical connection to the structure in a relatively large horizontal distance in front of said axis transverse plane. As a result, the lateral forces acting on the wheels or on the tire produce a moment component about the vertical axis of the axle body. Since at least in mass-produced vehicles, the connection of the trailing arm on the vehicle body for reasons of vibration isolation and sound insulation is realized by means of elastic bearings, it comes in driving conditions under lateral force to an undesirable elastic steering angle of the rear axle, in the direction of "oversteer". In order to reduce this unwanted elastic self-steering behavior of a torsion beam axis, although various measures are known, for example. The use of bearings with so-called. Starting ramp or hiring the main stiffness axes of the elastic bearings, or the provision of additional handlebars, but these measures can not fully satisfy. Thus, compensation for the elastic deformation of the bearings in the longitudinal direction due to the moment from the Radseitenkräften causes a transverse elastic displacement of the rear axle relative to the structure. The use of additional handlebars leads to a hardening of the basically desired suspension in Fzg.-longitudinal direction. Additional links also provide additional transmission paths for vibration from the axle to the vehicle body and, incidentally, can only conditionally contribute to increasing the rigidity of the connection about the vertical axis of the vehicle.

In addition to the modifications explained in the preceding paragraph, designs of composite-beam axles have become known, inter alia deal with the reduction of the required installation space and / or a simplified manufacturability and optionally also with a specific side guide. That's how it describes GB 2 351 050 A a equipped with leaf spring elements twist beam axle, which is characterized in comparison to composite steering axles with coil springs by a reduced space requirement. The EP 1 024 037 A1 also shows a torsion beam axle with leaf spring elements, wherein the cross member and the trailing arms and the leaf springs are made in one piece in a composite material. In the above paragraph described problem of the so-called. "Side force oversteer" is not addressed in these two documents and it is the support of the leaf spring elements on the vehicle body in the vehicle transverse direction formed slightly movable.

Furthermore, the shows EP 1 216 859 A2 a torsion beam axle with leaf spring elements, which additionally serve the side guide of the respective wheel, for which the respective leaf spring element is anchored with its in the direction of travel rear end in the vehicle transverse direction substantially rigidly to the vehicle body, while the front end of the leaf spring element longitudinally displaceable over a tab and in the transverse direction yielding suspended from the trailing arm. In the area of the vertical axis transverse plane defined by axes of rotation of the wheels, the respective trailing arm and the associated leaf spring element are connected to one another via a clamp, wherein this connection point lies approximately in the middle thereof over the length of the leaf spring.

As far as the possibility of a lateral guidance of the wheel of an axle by a leaf spring element is concerned, let it still be on DE 31 22 417 A1 pointed, which shows a special axle construction, however, can not be referred to as a torsion beam axis, as the two wheels associated trailing arm is not a rigid, but torsionally soft cross member firmly, but by a soft and soft to the vehicle's vertical axis pliant transverse transverse cantilever blade only extremely soft connected to each other. In particular, in this particular axle construction, the two wheels can spring independently of each other in the longitudinal direction and change their toe to each other by elastic deformation of the edgewise spring leaf. In order nevertheless to achieve an acceptable toe behavior, wheel-individual leaf springs are to control the respective toe-in and are fastened with one end to the respective trailing arm and supported with its other end longitudinally displaceable and transversely rigid on the vehicle body.

In the present case, for a twist beam axle in the usual sense, i. for an axle with wheel-individual trailing arms, which are firmly connected to each other via a rigid, but torsionally soft cross member, a simple design can be shown, with the known "side force oversteer" can be avoided (= object of the present invention).

The solution to this problem is characterized in that each leaf spring element is supported at both its ends such that its front end is fixedly connected to the associated trailing arm, while the rear articulation element is designed to transmit lateral forces and vertical forces between the leaf spring element and the vehicle body or but to permit movement of the leaf spring element in the vehicle longitudinal direction and the distances between the axial transverse plane and front elastic bearings of the trailing arm on the one hand and between the axial transverse plane and the rear attachment points of the leaf spring elements in conjunction with the selection of stiffness in vehicle Transverse direction of the front elastic bearings on the one hand and the selection of the stiffness in the vehicle transverse direction of the rear construction attachment points of the leaf spring elements in the structure on the other hand, the elasticities of the axis in the transverse direction and longitudinal direction of the vehicle are tuned so that under the influence of lateral forces on the wheels substantially no oversteer tendency is observed.

It is thus in addition to the transmission of Radseitenkräften on the front in the direction of travel (and thus lying in front of the Achsquerebene) elastic articulation points of the trailing arm and a proportion of Radseitenkräfte behind said axis transverse plane supported on the vehicle body. This can be structurally particularly simple and effective at the same time suitably designed and suitably connected to the vehicle body leaf spring element (left side and right side) done by this is fixed with its front in the direction of travel at the respective trailing arm substantially rigid and with its rear end , Which, viewed in the direction of travel, is located behind said axial transverse plane, is fastened to the vehicle body via a suitable articulation element, which can transmit essentially only transverse forces and vertical forces. This construction is much easier than that from the EP 1 216 859 A2 known axle principle, in which in addition to the supports at the ends of each leaf spring element and a support in the middle thereof on the trailing arm is required, via an above-mentioned bracket. The latter is not required in the torsion beam axle proposed here and yet can be formed with the transferability of shear forces in the rear, the specified properties coupling element a counter-torque to the front introduced by the trailing arm forces, while the transferability of vertical forces ensures the suspension spring effect of the leaf spring element , By substantially no longitudinal forces can be transmitted by the said hinge element, a restriction of the desired elasticity or desired suspension in the vehicle longitudinal direction does not occur.

The proposed leaf spring element, which may be, for example, a partially elliptical leaf spring, but alternatively also a suitably designed leaf spring package or a parabolic spring and / or a comparable spring element of a composite material, thus both the suspension of the vehicle body relative to the axis , as well as for the transmission of a portion of the Radseitenkräfte used. What the cushioning of the vehicle body with respect to the axis, this does not have to be done on this axis alone by said leaf spring elements; Rather, a support via coil springs or air springs or the like may be provided in parallel, although an already known from the prior art advantage of an axis according to the invention, namely an achievable space gain, primarily only with a leaf spring or the like. Can be achieved alone. With substantially longitudinal, widely arranged leaf springs can namely be obtained in a considerable amount of space compared to the coil springs commonly used.

With respect to the support of Radseitenkräften on the rear end of the leaf spring elements on Fzg. Structure, so the Radseitenkräfte be transferred to this axis over four points in the Fzg. Structure with reference to the entire axis, with two points (ie left and right) in the direction of travel before and two points (ie left and right) are behind the Radaufstandspunkt. In this case, by appropriate coordination of the distances between the axial transverse plane and the front elastic bearings on the one hand and between the Achsquerebene and the rear attachment points of the leaf spring elements on the other hand in connection with the selection of rigidity in particular in Fzg.-transverse direction of the front elastic bearings on the one hand and the Selection of the rigidity in particular in Fzg.-transverse direction of the rear attachment points of the leaf spring elements on the structure on the other hand a desired elastic self-steering behavior of a torsion beam axle according to the invention can be achieved. The position of the main rigidity axes of at least the front bearings, ie the coordination of the elasticities in the vehicle transverse direction and in the longitudinal direction of the vehicle can be chosen such that their position supports or at least less hampers a desired elastic self-steering behavior, in particular in that under the influence of lateral forces on the wheels substantially no tendency to oversteer is observed. In view of this, the transverse elasticity of said leaf spring elements should also be taken into account or interpreted, namely with regard to achieving a desired elastic lateral force steering behavior of a torsion beam axle according to the invention. In this case, there is the particular advantage that despite the possibility of a desired elastic side steering of the rear axle, a torsion beam axle according to the invention has a high yaw stiffness compared to the vehicle body. This minimizes unwanted steering in unilateral Radumfangskräften.

The leaf spring elements can - as already mentioned - be conventional leaf springs. To achieve very good cornering properties, parabolic springs (i.e., partially elliptical springs) may preferably be provided. The concept described can also be realized with spring elements made of composite material. A particular advantage in this context is that in the event of a break or generally a malfunction of a spring element, there is still sufficient axle guidance. Incidentally, another advantage of a torsion beam axle according to the invention is that tire lateral forces and the vertical forces of the suspension are introduced into the vehicle body by four points relative to the entire axle, which is conducive to lightweight construction and the use of softer, i. better vibration-isolating elastomeric bearings or the like. As bearings for the trailing arm on Fzg. Structure allows.

As regards the design of the said articulation element for the leaf spring element on the vehicle body, which is intended to transmit substantially only lateral forces and vertical forces, this may for example be in the form of a spring tab or in the form of a suitable plain bearing, with a spring tab substantially the vehicle transverse axis can be pivotably connected to the vehicle body in order to meet the requirement that the articulation element of the leaf spring element is at least partially displaceable in the vehicle longitudinal direction. This can be realized by the leaf spring elements additional body side Support, which also absorbs a portion of the lateral forces, ideally designed so that lateral forces and vertical forces are transmitted to the structure, however, a slight longitudinal movement of the torsion beam axle relative to the structure by this additional support is not hindered. Of course, the above-mentioned articulation elements can also be designed as a different intermediate element instead of the spring-strap type.

In addition, the invention will be further explained with reference to a preferred embodiment shown only in principle, wherein the attached FIG. 1 the side view of a torsion beam axle according to the invention and FIG. 2 the supervision of this axis shows.

The reference numeral 1l the left and the reference numeral 1r the right rear wheel of a two-lane motor vehicle or car otherwise not shown is marked, the direction of travel therefore corresponds to the arrow 2. These two rear wheels 1l, 1r are guided by a so-called. (Generally known to those skilled) twist beam axle relative to the vehicle body 3, not shown in detail, the left side and right side each having a substantially leading in the direction of travel 2 wheel-guiding trailing arm 4l, 4r , Each trailing arm 4l, 4r is supported by its end remote from the rear wheel 1l or 1r via an elastic bearing 5 on the vehicle body 3; Furthermore, the two trailing arms 41, 4r are firmly connected to one another via a cross member 6. In the Fig.2 Dashed axes of rotation of the rear wheels in this case essentially determine a so-called. Achsquerebene 9 (whose other dimension is the vertical direction).

In addition to these far explained and (except for here not existing coil springs) a torsion beam axis of common design forming elements left and right side respectively a leaf spring element 7 is provided here with its in the direction of travel 2 front end force and torque-resistant with the respective trailing arm 4l and 4r is connected, while the rear end in the direction of travel of this leaf spring element 7 is connected or supported by a trained here in the form of a spring tab coupling element 8 on Fzg. This articulation element 8 or this spring lug is pivotable relative to the vehicle body 3 about the transverse axis of the vehicle, so that a displacement of the respective leaf spring element 7 in Fzg.-longitudinal direction (ie in or against the direction of travel 2) is possible while forces in vehicle transverse direction (this is in the in Fig.2 represented horizontal plane perpendicular to Fzg.-longitudinal direction) are also transferred from the leaf spring element 7 in the Fzg. Structure 3 as vertical forces, which in the illustration to Fig.1 act perpendicular to Fzg.-longitudinal direction or direction of travel 2.

Due to the transferability of vertical forces in the articulation elements 8, the two leaf spring elements 7 can take over the function of the usual suspension springs for the Fzg. Structure 3, after it with its front end fixed (ie capable of transmitting forces and moments in any direction) with the respective trailing arm 4l and 4r are connected, while due to the transferability of lateral forces in the articulation elements 8 on the rear wheels 1l, 1r acting on the tire contact surface lateral forces now not only on the trailing arm 4l, 4r on the elastic bearings 5 in the direction of travel 2 considered before Achsquerebene 9 are introduced into the vehicle body 3, but also behind the Achsquerebene 9 on the leaf spring elements 7 and the coupling elements 8. This is much better a desired elastic self-steering behavior of this torsion beam axis representable, which should be noted that quite a variety of Details differ d can be designed from the above explanations without departing from the content of the claims.

Claims (3)

1. A twist beam axle of a two-track vehicle with a left-hand and a right-hand trailing link (4l, 4r) guiding the respective rear wheel (1l, 1r), which trailing links are connected to one another by means of a traverse member (6) and are mounted by their leading end remote from the rear wheel (11, 1 r), observed in the direction (2) of travel, directly or indirectly to the vehicle bodywork (3), as well as with a left-hand and a right-hand leaf spring element (7) which is substantially oriented in each case in the longitudinal direction of the vehicle and which counteracts a substantially vertical displacement of the rear wheel (1l, 1r) in the direction of the vehicle bodywork (3) with a spring force and is connected by its leading end in the direction of travel to the associated trailing link (4l, 4r) and is supported on the vehicle structure (3) by its rear end, observed in the direction (2) of travel, behind the axial transverse plane (9) defined substantially by the rotational axes of the rear wheels (1l, 1r), by means of a coupling element (8) receiving transverse forces, characterised in that each leaf spring element (7) is supported at its two ends in such a way that the leading end thereof is rigidly connected to the associated trailing link (4l, 4r) while the rear coupling element (8) is designed to transmit or absorb transverse forces and vertical forces between the leaf spring element (7) and the vehicle bodywork (3), but to allow a movement of the leaf spring element (7) in the longitudinal direction of the vehicle, and wherein the spacings between the axial transverse plane (9) and the leading elastic bearings (5) of the trailing links (4l, 4r), on the one hand, and between the axial transverse plane (9) and the rear bodywork connection points of the leaf spring elements (7), on the other hand, in connection with the selection of the rigidity in the transverse direction of the vehicle of the leading elastic bearings (5), on the one hand, and the selection of the rigidity in the vehicle transverse direction of the rear bodywork connection points of the leaf spring elements (7) on the bodywork, on the other hand, and the elasticities of the axle in the transverse direction and longitudinal direction of the vehicle are matched to one another in such a way that under the action of lateral forces on the wheels, substantially no over-steering tendency is to be observed.
2. A twist beam axle according to claim 1, characterised in that the rear coupling element (8) is configured in the form of a slide bearing or a spring lug, which can be pivoted about the transverse axis of the vehicle and can thus be displaced proportionately in the longitudinal direction of the vehicle.
3. A twist beam axle according to claim 1 or 2, characterised in that the leaf spring element (7) is configured as a leaf spring package or as a parabolic spring and/or is a comparable spring element made of a composite material.

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